A microfluidic chip functions to conduct various experiments at once by letting a fluid flow out through a microfluidic channel. In detail, after a microfluidic channel is manufactured using a material, such as plastic, glass, silicon, and so on, a fluid, for instance, a liquid sample, is moved through such a channel, and then, mixing, separation, refinement, reaction and analysis are executed in a plurality of chambers inside the microfluidic chip. Because various experiments which were conventionally executed in a laboratory are executed in the small chip, the microfluidic chip is also called “lab-on-a-chip”.
The microfluidic chip can create cost and time reduction effects in the fields of pharmaceuticals, biotechnology, medicines and so on, and enhance accuracy, efficiency and reliability. For instance, compared with the conventional methods, the microfluidic chip can remarkably reduce the usage of protein and expensive reagents used for DNA analysis so as to show reduction effect of considerable expenses. Moreover, the microfluidic chip uses fewer amounts of protein samples or cell samples than the conventional methods, thereby reducing waste of samples.
In the meantime, the fluid used in the microfluidic chip may generate bubbles by micro cavities or pinholes formed inside the microfluidic chip while a reactive fluid, such as a sample reagent or a specimen, is injected. Particularly, the polymerase chain reaction (PCR) is executed using the microfluidic chip, the PCR accompanies a heat supply step, when the fluid is heated, the volume of small bubbles generated during injection is expanded to grow into bubbles of a larger size or a plurality of the small bubbles are joined together into one big bubble, so that a large quantity of bubbles are generated inside the fluid. If such bubbles are located in an optical measuring area, they may be a main cause to reduce optical signal sensitivity of a reaction product. Furthermore, if the bubbles move irregularly, it may cause decrease in reliability of the optical signal.
Referring to FIG. 1, optical signal sensitivity is decreased due to bubbles contained in the fluid during the process of reaction inside a conventional microfluidic chip. That is, because the miniaturized microfluidic chip has a space of a reaction chamber which is small for the size and the number of bubbles generated, there is high probability that the generated bubbles are located above any optical measuring area arranged in the reaction chamber. Additionally, as shown in FIG. 1, if bubbles are located inside the optical measuring area, the bubbles lower sensitivity of the optical signal because blocking the optical signal emitted from the reaction product.
Therefore, in order to realize miniaturization of the reaction chamber like the microfluidic chip, solutions to the problems arising from reduction and ununiformity of optical signal sensitivity in order to secure reliability of measurement results are required.